The Master's thesis deals with the topic of aggression in children. It focusses on the different kinds of aggression, specifics of aggression in children in their developmental stages, developmental trajectories of aggression, gender differences in aggression, determinants of aggression, theories of origin of gender differences, and international comparisons of aggression. The objectives of the research was to examine specifics of aggression in a Czech sample group, compare Czech results with the results of other countries (Greece, France, Germany, Italy, Turkey, China, India, Venezuela, Colombia, Mexico and Peru), and examine the effect of age, gender, and sibling birth order on aggression. The mean of factors of aggression in the Czech sa...